1. Field of the Invention
Generally, the present disclosure relates to the monitoring of manufacturing processes, and, more particularly, to managing information in a manufacturing environment, such as a semiconductor facility, in which a plurality of different product types and process and metrology tools are operated, in order to improve yield, quality and performance analysis.
2. Description of the Related Art
Today's global market forces manufacturers of mass products to offer high quality products at a low price. It is thus important to improve yield and process efficiency to minimize production costs. This holds especially true in industrial fields in which highly complex process tools operate on complex products according to specified process parameters that may vary between different product types. A prominent example in this respect represents the field of semiconductor fabrication, since, here, it is essential to combine cutting edge technology with mass production techniques. It is, therefore, the goal of semiconductor manufacturers to reduce the consumption of raw materials and consumables for a prescribed product quality while at the same time improve process tool utilization. The latter aspect is especially important since, in modern semiconductor facilities, equipment is required which is extremely cost intensive and represents the dominant part of the total production costs.
Integrated circuits, as one example for a mass product, are typically manufactured in automated or semi-automated facilities, thereby passing through a large number of process and metrology steps to complete the device. The number and the type of process steps and metrology steps a product, such as a semiconductor device, has to go through depends on the specifics of the product to be fabricated. For example, a typical process flow for an integrated circuit may include a plurality of photolithography steps to image a circuit pattern for a specific device layer into a resist layer, which is subsequently patterned to form a resist mask for further processes for structuring the device layer under consideration by, for example, etch or implant processes, deposition processes, heat treatments, cleaning processes and the like. Thus, layer after layer, a plurality of process steps are performed based on a specific lithographic mask set for the various layers of the specified device. For instance, a sophisticated CPU requires several hundred process steps, each of which has to be carried out within specified process margins so as to fulfill the specifications for the device under consideration. Since many of these processes are very critical, a plurality of metrology steps have to be performed to efficiently control the quality of the process flow. Typical metrology processes may include the measurement of layer thickness, the determination of dimensions of critical features, such as the gate length of transistors, the measurement of dopant profiles, the determination of electrical characteristics and the like. As the majority of the process margins are device-specific, many of the metrology processes and the actual manufacturing processes are specifically designed for the device under consideration and require specific parameter settings at the adequate metrology and process tools.
In many production plants, such as semiconductor facilities, a plurality of different products types are usually manufactured at the same time, such as memory chips of different design and storage capacity, CPUs of different design and operating speed and the like, wherein the number of different product types may even reach a hundred and more in production lines for manufacturing ASICs (application specific ICs). Since each of the different product types may require a specific process flow, specific settings in the various process tools, such as different mask sets for the lithography, different process parameters for deposition tools, etch tools, implantation tools, chemical mechanical polishing (CMP) tools, furnaces and the like, may be necessary. Consequently, a plurality of different tool parameter settings and product types may be encountered simultaneously in a manufacturing environment.
The manufacturing process flow in a complex manufacturing facility is usually controlled by a supervising control system, which is frequently called a Manufacturing Execution System (MES). In a correspondingly controlled manufacturing environment, the process flow, that is, the scheduling of products, the process and metrology tools used, the various process recipes, i.e., the set of parameters of a process performed in a specific tool to achieve a desired process result, the consumables and the raw materials are controlled on the basis of specification limits, which describe the limits between which the respective object to be controlled has to be maintained in order to provide high quality and yield.
The currently practiced process control is, however, usually performed on the basis of individual process modules in an attempt to individually improve the process result of these modules. For instance, the lithography module, involving resist application and treatment, the actual exposure process, post-exposure treatments, resist development and the like, the etch module for transferring resist feature into a process layer and the like, may be monitored with respect to excursions from the specification limits or target tool parameter settings, wherein statistical process control techniques (SPC), advanced process control (APC) strategies and the like may be used for maintaining the individual process modules within the specification limits. Thus, a large amount of process data, such as measurement data from respective metrology tools associated with the various process modules, is created. Various systems have been developed for obtaining and managing the process information obtained from the individual process modules, such as Engineering Request Forms (ERF), Decision Records (DR), material analysis reports, analysis results and the like. Moreover, tool or process excursions or other specific events in the manufacturing environment are typically recorded manually or in proprietary systems. In this way, yield and performance improvement of individual modules may be achieved by, for instance, analyzing data of processed products, tool information and the like. The assessment of interrelated process modules or the process flow as a whole may, however, be very difficult and suffer from a reduced reliability due to the highly “modular” character of the information available for process optimization.
The present disclosure is directed to various systems and methods that may avoid, or at least reduce, the effects of one or more of the problems identified above.